Williams said Johnson, accused of posing as a 15-year-old sophomore at New Life Christian School in Longview, Texas, told him she was 18 years old.

KLTV

PHOTO: Rickie Williams tells KLTV that he is the boyfriend of Charity Johnson.

New details continued to emerge days after Johnson, who allegedly enrolled at the high school in October using the name Charity Stevens, was arrested after allegedly giving Longview Police a fake name and age.

Osarieme Obaseki, who runs What About Us, a non-profit group for women and girls in need, told ABC News Johnson first called her last month, claiming to be a 14-year-old who needed help. The pair began talking on the phone and Obaseki, who lives in Dallas, gave Johnson advice and became a motherly figure during their conversations, she said.

Obaseki, 40, said she never spoke to Tamica Lincoln, who was Johnson’s guardian in Longview at the time.

“Soon, I began to be called, ‘Mom,’” Obaseki said. “I would hear her say little things like, ‘What if I popped up in Dallas?’”

That’s exactly what happened, Obaseki said.

Johnson took a train to Dallas to visit Obaseki for Mother’s Day, even bringing her a homemade, construction paper card, Obaseki said. Over the weekend, Obaseki became suspicious.

“I can’t really explain it, but I listened to her and knew something wasn't right. Her stories were changing,” Obaseki said. “When my sister saw her, she said, ‘That is not a child, look at her body!'”

Courtesy Osarieme Obaseki

PHOTO: Charity Johnson (left) with Osarieme Obaseki in Dallas on Mother's Day weekend.

Obaseki said she suspected there were other people Johnson called “Mom.”

“It’s just been a lot of lies and cover-up,” she said. "Nobody I spoke to has said it’s ever been a financial situation. She had money! It’s not that, at all."

Obaseki contacted Lincoln and the pair determined Johnson was lying about her age after calling McDonald’s, where Johnson worked, she said.

“The manager verified she had two applications on file," Obaseki said. "One birthday was 1982, the other was 1979. Either way, it proved she’s too old to be in high school.”

Johnson’s real birthday was November 1979, police said.

ABC News could not reach Johnson or any of her family members for comment. Police said she was being held on $500 bond at Gregg County Jail, accused of failure to ID herself and giving false and fictitious information, and had not yet had a lawyer appointed to represent her.

In the meantime, other people who knew Johnson have been coming forward.

"We have all wondered about her because she's always quiet and to herself, you know," Roshunda Floyd, who works at the Walmart in Longview, told KLTV.

Johnson worked at the McDonald's inside the Walmart.

Obaseki was eager to warn people about the woman she believed had lied about her age, on the possibility there might be prior cases.

“I want people to be aware of what she has done,” she said. "This goes farther than Longview and Dallas."

Obaseki added that there’s one moment from Johnson’s visit she can’t forget.

“The irony of it is that she writes," Obaseki said, "and she would say, ‘Momma, I’m going to be famous one day.’ And well, you’re famous! She’s famous!”